ABT-229 is a new drug that belongs to the class of macrolides with motilin agonist activity and without significant antibotic activity. Treatment of diabetic gastroparesis with motility agents have met with some success. ABT-229 has the potential to alter the pathophysiology and improve the symptoms in patients with diabetic gastroparesis without altering the normal gut flora. The objectives of this study are to assess the efficacy of four different doses of ABT-229 compared to placebo for the treatment of postprandial digestive symptoms and to assess the safety of ABT-229 in patients with insulin-requiring diabetes. Patients will be required to refrain from the use of other prokinetic and anti-secretory agents during the study. At each visit, patients will have laboratory tests, pregnancy tests (for females of child bearing potential), pharmacokinetic plasma samples, electrocardiograms, and physical examinations including vital signs. In addition patients will be asked to 1) complete a symptom questionnaire at all visits 2) keep a daily diary to monitor glycemia control and insulin dosing and 3) report physician office visits, ER visits, or hospital visits, since the previous study visit. Patients will be asked to compelte the NDI Qualify of Life questionnaire and the 13C-Octanoic acid breath test (13C-OBT) procedures will be performed on the GCRC. The GCRC dietary staff will prepare the standarized meal.